C#继承，抽象类代码如何实现

Question

C#继承，抽象类代码如何实现
代码要求如下，C#继承，抽象类代码如何实现，请给完整代码

Answer 1

using System;
 
namespace Shape
{
    public abstract class Shape
    {
        public abstract double GetArea();
        public abstract double GetCircumference();
    }
    public class Circle : Shape
    {
        public double x { get; set; }
        public override double GetArea()
        {
            return Math.Round(Math.PI * Math.Pow(x, 2), 4);
        }
        public override double GetCircumference()
        {
            return Math.Round(2 * x * Math.PI, 4);
        }
    }
    public class Rectangle : Shape
    {
        public double x { get; set; }
        public double y { get; set; }
        public Rectangle(double x, double y)
        {
            this.x = x;this.y = y;
        }
        public override double GetArea()
        {
            return x * y;
        }
        public override double GetCircumference()
        {
            return (x + y) * 2;
        }
    }
    public class Square : Rectangle { public Square(double x) : base(x, x) { } }
 
    public class Triangle : Shape
    {
        public double x { get; set; }
        public double y { get; set; }
        public double z { get; set; }
        public Triangle(double x, double y, double z)
        {
            if (x + y > z && x + z > y && y + z > x)
            {
                this.x = x;this.y = y;this.z = z;
            }
            else Console.WriteLine(x+","+y+","+z+ "无法构成三角形！");
        }
        public override double GetArea()
        {
            double p = (x + y + z) / 2;
            return Math.Round(Math.Sqrt((p * (p - x) * (p - y) * (p - z))), 4);//保留4位小数，保留位数改这里
        }
        public override double GetCircumference()
        {
            return x + y + z;
        }
    }
 
 
    class Program
    {
        public static void ShowInfo(Shape p)
        {
            Console.WriteLine(String.Format("{0,-15}{1}", "周长：" + p.GetCircumference(), "面积：" + p.GetArea()));
        }
        static void Main(string[] args)
        {
            ShowInfo(new Circle { x=5 });
            ShowInfo(new Rectangle(4, 5));
            ShowInfo(new Square(4));
            ShowInfo(new Triangle(3, 4, 5));
            Console.ReadKey();
        }
    }
}